Joints of the Thoracic Limb

Question 1

Synovial Joints

Answer 1

Formed by two or more bones

Cavity between bones

Cartilaginous articulations

Joint capsule= holds everything together

Synovium = Produce synovial fluid

Stabilized by muscles and/or ligaments

Question 2

Synsarcosis

Answer 2

“fleshy” attachment of the thoracic limb to the trunk

Question 3

What are the joints of the thoracic limb and elbow attachments?

Answer 3

Shoulder joint

Elbow joint

Carpal joint

Digital joints: Metacarpophalangeal joint Proximal interphalangeal joint Distal interphalangeal joint

Question 4

Synovial Structure Composition

Answer 4

Filled with synovial fluid Viscous fluid Nourishes and lubricates the joint

Question 5

Synovial Joint Capsule

Answer 5

Synovial envelope that encloses a joint Fibrous can restrict movement Pouches

Question 6

Synovial bursae

Answer 6

Synovial sac lying between a tendon or muscle and an adjacent bony prominence

Question 7

What are tendon sheaths?

Answer 7

Synovial sac that completely surrounds a tendon

Question 8

What are the functions of ligaments in respect to joints?

Answer 8

Attach bone to bones

Stabilize and support the joints

*** Make sure that you specify the joint and ligament when ansswering the queston***

Question 9

Retinacula

Answer 9

Fibrous bands of connective tissue that bind tendons

Question 10

Carpal Canal

Answer 10

“Passage way” - tunnel for tendons

Flexor carpi radialis m. (muscle ends on MC2 or MC3)

Digital flexor tendons and their synovial sheaths:

• Superficial digital flexor tendon
• Deep digital flexor tendon

Question 11

Blood Vessels and Nerves of the Carpal Canal

Answer 11

Median and radial aa. Median and ulnar nn.

Question 12

Boundaries of the Carpal Canal

Answer 12

Palmar carpal ligament

Flexor retinaculum

Accessory carpal bone

** need to cut the flexor retinaculum to expose the carpal canal**

Question 13

Digital Joints

(Very important in large animals)

Answer 13

Metacarpophalangeal joint

• Distal extremity of the metacarpal bone –> proximal extremity of the proximal phalanx (p1)
• Fetlock joint in horses

Proximal interphalangeal joint

• Distal extremity of proximal phalanx –> proximal extremity of middle phalanx
• Pastern joint in horses

Distal interphalangeal joint

• Distal extremity of middle phalanx –> proximal extremity of distal phalanx
• Coffin joint in horses

Range of motion = flexion and extension

Supporting ligaments:

• Medial and lateral collateral ligaments
• Annular ligaments
  
  • Palmal annular ligament of fetlock joint (horses)
  • proximal digital annular ligament of proximal phalanx (horses)
  • distal digital annular ligament of middle phalanx

Question 14

Metacarpophalangeal joint *

Answer 14

Distal extremity of the metacarpal bone–> proximal extremity of the proximal phalanx

**Fetlock joint in horses

Question 15

Proximal interphalangeal joint

Answer 15

Distal extremity of the proximal phalanx –> proximal extremity of the middle phalanx (p2)

Pastern joint in horses

Question 16

Distal interphalangeal joint

Answer 16

Distal extremity of the middle phalanx –> proximal extremity of the distal phalanx

Coffin joint in horses

Question 17

Range of Motion for Digital Joints

Answer 17

Flexion and extension

Question 18

What are the supporting ligaments of digital joints?

Answer 18

Medial and lateral collateral ligaments of the digital joint

Annular ligaments ****

• Brace digital flexor tendons in MC & P1 & P2

Horse:

Palmar annular ligament at the fetlock joint (btwn MC & P1)

Proximal digital annular ligament of P1 (pastern joint)

Proximal digital annular ligament of P2

Question 19

Where are Dorsal Elastic Ligaments located?

Answer 19

Located on each side of the common digital extensor tendon

Mainly in cats

Keep the claws retracted

Claws are protruded by simaltaneous contraction of the deep digital flexor.

Question 20

Function of Dorsal Elastic Ligaments *

Answer 20

Keeps claws retracted Claws are protruded by simultaneous contraction of the deep digital flexor

Question 21

Annular ligaments

Answer 21

Brace the digital flexor tendons

Proximal digital annular ligament *

Distal digital annular ligament

Question 22

Interdigital Ligament in Ruminants

Answer 22

2- very close to the surface of the skin

Proximal interdigital ligament (flimsy)

Distal interdigital ligament (thick)

** Support the digits & prevent them from spreading**

** Can’t compromise the integrity of that ligament because Cows wont be able to stand**

Question 23

Navicular Bursa in Horses

Answer 23

• Located between the navicular bone & deep digital flexor tendon m.
• protects the deep digital flexor tendon from excessive friction and pressure against the navicular bone
• This is a common site of inflammation and when distended bulges above the proximal seasamoid bones
• Bursitis due to injury
• Puncture is most common

Question 24

Glenohumeral (Shoulder) Joint

Answer 24

Articular surfaces:

• Glenoid cavity of the scapula
• Humeral head

Range of motion: Flexion and extension

Supporting Ligaments:

• Joints stabilized by muscles in this region
• Supraspinatus, infraspinatus, and subscapularis mm.

Associated structures:

• Glenohumeral ligaments
• Transverse Humeral Retinaculum
• Synovial Structures

Question 25

Associated structures of the Glenohumeral Joint

Answer 25

Synovial structures:

• Infraspinous bursa
• Tendon sheath of bicipital tendon
• Horses= bicipital bursa instead of bicipital tendon

Glenohumeral Ligaments:

• Medial and lateral

Transverse humeral retinaculum

• Holds biceps tendon in bicipital groove

Question 26

Why is the bicipital bursa easily accessed in horses?

Answer 26

• Horses don’t have an acromion (part of Deltoideus m.)
• Bicipital bursa is closely associated with the bicipital tendon

Question 27

Cubital (Elbow Joints)

Answer 27

Articular surfaces:

• Humeral condoyle
• Head of radius and trochlear notch of ulna
• Articular circumrence of the radius and radial notch of the ulna

Range of motion : Flexion and extension

Supporting Ligaments:

• Medial and lateral collateral ligaments (straight up and down)

Synovial structures: Caudodorsal pouch

Question 28

Radioulnar Joint

(Joint between radius and ulna)

Only applies to the DOG!

(pronation/supination)

Answer 28

Articular surfaces:

• Articular circumfrence of the radius and radial notch of the ulna
• Articular circumfrence of the ulna and ulnar notch of the radius

Range of motion: Supination & Pronation

Supporting Ligaments:

• Interosseous ligament

Question 29

Carpal (Wrist) Joint

Answer 29

Composite Articulations:

• Antebrachiocarpal joint (btwn forearm and 1st row of carpal bones)
• Middle carpal joint (btwn proximal & distal row of carpal bones)
• Intercarpal joint (spaces btwn carpal bones)
• Carpometacarpal joint (line btwn distal row and metacarpal bones)

Range of Motion:

Flexion & Extension

• Antebrachiocarpal and middle carpal*

Supporting Ligaments:

• Medial and lateral collateral ligaments
• Palmar carpal ligament- skinny tendon covering the carpal canal
• Short ligaments- just know they exist

Question 30

Associated Structures of the Carpal Joint

Answer 30

Synovial structures:

• Common joint capsule–> separation between synovial compartaments
• Exception: Middle Carpal Joint communicates with carpometacarpal joint

Tendon & tendon sheaths of extensors & flexors

Retinacula:

Extensor retinaculum–> extensor surface

Flexor retinaculum –> palmer surface

Question 31

Clinical Application: Carpal Injection

Answer 31

In order to access the carpometacarpal joint, you should inject in the middle carpal because the middle carpal and carpometacarpal joints communicate with eachother.

True for all species

Carpometacarpal joint is immovable